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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 308 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.433 + 136 =
  2. 2.143 + 351 =
  3. 3.465 + 601 =
  4. 4.567 + 329 =
  5. 5.724 − 546 =
  6. 6.712 + 604 =
  7. 7.765 − 232 =
  8. 8.578 − 392 =
  9. 9.517 − 345 =
  10. 10.495 + 248 =
  11. 11.700 − 223 =
  12. 12.430 − 255 =
  13. 13.403 + 241 =
  14. 14.716 − 314 =
  15. 15.958 − 804 =
  16. 16.252 + 168 =
  17. 17.219 + 218 =
  18. 18.545 − 373 =
  19. 19.426 − 206 =
  20. 20.184 + 141 =
  21. 21.535 − 387 =
  22. 22.604 − 113 =
  23. 23.512 − 381 =
  24. 24.739 + 541 =
  25. 25.823 − 609 =
  26. 26.468 − 148 =
  27. 27.262 + 185 =
  28. 28.324 + 392 =
  29. 29.974 − 848 =
  30. 30.261 + 594 =
  31. 31.323 + 292 =
  32. 32.781 + 266 =
  33. 33.483 + 564 =
  34. 34.433 + 264 =
  35. 35.586 − 183 =
  36. 36.541 + 219 =
  37. 37.754 − 185 =
  38. 38.125 + 329 =
  39. 39.432 − 113 =
  40. 40.952 − 314 =

Answer key

  1. 569
  2. 494
  3. 1066
  4. 896
  5. 178
  6. 1316
  7. 533
  8. 186
  9. 172
  10. 743
  11. 477
  12. 175
  13. 644
  14. 402
  15. 154
  16. 420
  17. 437
  18. 172
  19. 220
  20. 325
  21. 148
  22. 491
  23. 131
  24. 1280
  25. 214
  26. 320
  27. 447
  28. 716
  29. 126
  30. 855
  31. 615
  32. 1047
  33. 1047
  34. 697
  35. 403
  36. 760
  37. 569
  38. 454
  39. 319
  40. 638

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